I'm not sure I understand the question as yet. Are you asking how can one know who The One, True God is (a matter of sorting out gods that leads to atheism) or do you mean, can you prove or disprove the existence of a god generally?

I started a discussion over at debatingchristianity about a week ago. It's gotten over 4500 views so far which is the most rapid increase in viewership the site has ever had, so it must be interesting. If you're interested, it is a discussion where I posed the question,

"How do I know your God is The One, True God"?

I know at least SteveInCO has visited (he uses the same name there) because he commented there. It's a deconversion conversation staged on a blog (not realistic) but it gives you an idea of how you might try to argue for or against a god in a way that is actually effective as opposed to rhetorical, humorous, tongue in cheek, speaking to the choir, etc.